This invention pertains to synergistic herbicidal combinations, particularly such combinations for use in controlling weeds in a rice crop.
Molinate (S-ethyl hexahydro-1H-azepine-1-carbothioate) is a thiocarbamate herbicide which has been used to control weeds in rice crops for a number of years, and is generally sold under products bearing the trademark ORDRAM.RTM.. In different formulations and strengths, molinate is applied pre-plant, pre-flood or post-flood to control a wide range of weeds in rice crops, and is generally applied at rates ranging from about 500 to about 11,000 g/ha. However, as with many pesticides, it would be desirable to be able to achieve weed control while using a lower application rate of molinate. This could also result in less impact upon the environment and/or upon workers handling the product.
It has now been found that, surprisingly, combining of a much lower amount of the herbicide oxyfluorfen with molinate can produce a synergistic effect such that equivalent weed control can be obtained with a lesser amount and/or application rate of molinate.
Oxyfluorfen or 2-chloro-1-(3-ethoxy-4-nitrophenoxy)-4-(trifluoromethylbenzene) is a diphenyl ether herbicide sold primarily under the trademark GOAL.RTM.). Primarily, oxyfluorfen is sold for control of weeds in fruit, nut and vegetable crops, and in cotton. It is not usually used for control of weeds in rice crops because the rate of application needed to control weeds tends to cause unacceptable damage to the rice. Oxyfluorfen is used, however, in China on a small scale to control weeds in rice. In accordance with the present invention, however, the use of oxyfluorfen in an amount which produces substantially no phytotoxicity to a rice crop, in combination with molinate, particularly a lesser amount or lower application rate of molinate than is normally used, produces a synergistic effect, resulting in good control of weeds in rice crops in either pre-flood or post-flood applications.